*Monticello Classroom. [http://classroom.monticello.org/teachers/gallery/image/344/Jeffersons-notes-on-the-weather-at-Monticello-July-1814/ "Weather Memorandum Book, July 1814."] An image of the original manuscript from the Coolidge Collection of Thomas Jefferson Manuscripts, Massachusetts Historical Society.

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*Monticello Classroom. [http://classroom.monticello.org/teachers/gallery/image/344/Jeffersons-notes-on-the-weather-at-Monticello-July-1814/ "Weather Memorandum Book, July 1814."] An image of the original manuscript from the Coolidge Collection of Thomas Jefferson Manuscripts, Massachusetts Historical Society.

Revision as of 15:45, 3 December 2009

For the more than fifty years that Thomas Jefferson was a systematic weather observer, Monticello was the focus of his efforts to understand the American climate.[1] Well before 1776, the date of his earliest surviving meteorological diary, he was carefully assembling information on the weather of Virginia and making his own observations at Williamsburg and Monticello. The fruits of these endeavors appeared in the chapter on climate in his Notes on the State of Virginia, which, when published in 1785, established his membership in the international fraternity of scientists and natural philosophers.

From 1776 Jefferson kept a consistent and,
with inevitable interruptions, continuous record
of his weather observations, in America,
in Europe, and even in the mid-Atlantic. His practices
and those of National Weather Service
observers today are basically the same: to
measure precipitation and to record the daily
temperature range. The modern station at
Monticello requires one daily reading of two
thermometers which indicate maximum and
minimum temperatures for the preceding twenty-four hours. Jefferson had no need of a
maximum-minimum thermometer because he
rose every day at dawn, which he considered
the coldest time of day. He described his daily
ritual, the results of which are illustrated in
the page from his meteorological diary here reproduced (in the See Also section below),
as follows: "My method is to make
two observations a day, the one as early as possible
in the morning, the other from 3. to 4.
aclock, because I have found 4. aclock the hottest
and day light the coldest point of the 24.
hours. I state them in an ivory pocket book in
the following form, and copy them out once a
week. The 1st. column is the day of the month.
The 2d. the thermometer in the morning. The
4th. do. in the evening. The 3d. the weather in
the morning. The 5th do. in the afternoon. The
6th is for miscellanies, such as the appearance
of birds, leafing and flowering of trees, frosts
remarkeably late or early, Aurora borealis, &c.
In the 3d. and 5th. columns, a. is after: c,
cloudy: f, fair: h, hail: r, rain: s, snow. Thus
c a r h s means, cloudy after rain, hail and
snow. Whenever it has rained, hailed or
snowed between two observations I note it
thus, f a r (i.e. fair after rain), c a s (cloudy
after snow &c.) otherwise the falling weather
would escape notation. I distinguish weather
into fair or cloudy, according as the sky is
more or less than half covered with clouds."

Jefferson went beyond the scope of the
present weather station by attempting to collect
data on winds and humidity, but he was hampered by the imperfect instruments then
available to him. An accurate anemometer was
not invented until 1850 and the hygrometer
was not perfected in his lifetime. While in
Paris Jefferson experimented with three different types of hygrometer, recording their readings
daily for five years in the hope of finding
an instrument which could be trusted to provide
accurate comparative observations. His initially patriotic motive was to topple one of
the two "pillars" of the theory of degeneracy
of animal life in America advanced by the Comte de
Buffon and other European scholars--America's
alleged excessive humidity. Also in his
role as champion of the North American continent,
Jefferson began in Paris to compile a
record of the ratio of cloudy to sunny skies.
After a five-year residence in France, he had
proved to himself that America completely
eclipsed Europe in the sunshine contest and he
appreciated more than ever the "cheerful"
sunny climate of his native country.

While responding to international rivalry
over climate was at times irresistible, Jefferson's motives for recording comparative
weather data were of course much grander.
The patient accumulation of details of what
he called "the indexes of climate"--temperature,
prevailing winds, precipitation, and related
biological events like the flowering of
plants and the migration of birds--was intended
to form the foundation of a reliable
theory of weather and climate. The advancement of meteorology, which in Jefferson's
opinion had made the least progress of any
science in his lifetime, was at the root of his
own data gathering and inspired him to enlist
everyone he could in the process. In the 1770s
he had planned to provide a thermometer to
one dependable deputy for each county of Virginia
and to exact from them twice-daily observations
of temperature and wind direction.
This ambitious scheme, which was meant to be foundation of a national network of weather
observers, was frustrated by the Revolutionary
War, but ever afterward Jefferson called on
every available watchman to take up his own
observation post. Young Americans making
the grand tour of Europe, stationary scholars,
official explorers, sons-in-law, daughters, and
grandchildren, were all enlisted to swell the
stream of information. When Jefferson left for
Europe in 1788, he practically commanded the
two James Madisons--the professor in Williamsburg
and the politician in Orange
County--to carry on the daily meteorological
ritual in his absence. An important clause of
his official instructions to Lewis and Clark in
1803 enjoined them to observe "climate as
characterized by the thermometer, by the proportion
of rainy, cloudy & clear days, by lightening,
hail, snow, ice, by the access & recess of
frost, by the winds prevailing at different
seasons, the dates at which particular plants
put forth or lose their flowers, or leaf, times of appearance of particular birds, reptiles or
insects."

If in his lifetime Jefferson never found his
own equal in committed and unfaltering attention
to the details of his climate, his dream of
simultaneous observations across the land is
real today. Monticello is one of 12,000 weather
stations now under the National Weather Service,
which has claimed Jefferson as the "father
of weather observers." And it is unquestionable
that Jefferson considered his observations
a pleasure as well as a duty, especially the contemplation
of his own climate at Monticello.
"Climate is one of the sources of the greatest
sensual enjoyment," he wrote while President.
And from Lake Champlain in May of 1791 he
penned a well known tribute to his native air:
"On the whole I find nothing anywhere else in point of climate which Virginia need envy to
any part of the world. Here they are locked up
in ice and snow for 6. months. Spring and
autumn which make a paradise of our country
are rigorous winter with them, and a tropical
summer breaks on them all at once. When we
consider how much climate contributes to the
happiness of our condition, by the fine sensation
it excites, and the productions it is the
parent of, we have reason to value highly the
accident of birth in such a one as that of
Virginia."